A golf shoe, for example, has metal spikes which are screwed into a shoe sole to be secured thereto. It has been pointed out that this kind of shoe has a problem that the metal spikes could damage greens of a golf course. Therefore, a recent trend is to use spikeless shoes having a shoe sole formed integrally with protrusions made of a plastic material. However, such shoe sole structure having protrusions integral with the sole requires to replace the whole shoe sole when the protrusions have worn.
To solve this problem, the structure may be that spikes made of a plastic material are screwed into shoe soles. However, in the case where such plastic spikes are screwed into the shoe sole in a manner similar to that of metal spikes, there may be a practical problem that loosening may easily occur in use, due to the physical properties of the material used for the spikes. To solve the problem, Japanese patent laid-open publication No. Hei 11-9306 has proposed that an sporting shoe spike can consist of a body made of a plastic material, and a core made of a metal material. In the proposed structure, the body is comprised of a flange-shaped portion and a threaded stud which extends from one surface of said flange-shaped portion and has a thread on an outer surface of the stud. An axial bore is formed to extend through a flange-shaped portion and the threaded stud, while a slit is formed to extend axially to the free end of the stud. A core is inserted into the axial bore to be fixed to the body. The core is configurated to make the stud to expand radially outwardly when inserted in the axal bore of the body. Further, the flage-shaped portion of the spike body has a plurality of spike protrusions formed on the other surface thereof opposite the threaded stud.